Disclosed herein are lactic acid esters of polyvinyl alcohol and a process for making such esters. The lactic acid esterified polyvinyl alcohol is useful in films, moldings and adhesives.
Polyvinyl alcohol is an article of commerce and useful in fibers, adhesives and textile and paper sizing. However, one of the drawbacks of polyvinyl alcohol is that it is not melt processible, or if modified to make it melt processible, it is often not soluble in cold water and not crystalline, which are desirable properties of this types of polymer.
Simple (alkyl) esters of polyvinyl alcohol are well known, for example, the commercially available poly(vinyl acetate).
U.S. Pat. No. 3,249,572 describes a composition (Example II, Formulation 14) which includes polyvinyl alcohol, polyethyleneimine, water and lactic acid. This prior art patent discloses a system in which the acid improves the properties of the adhesive described by inhibiting the crosslinking of the polyethyleneimine present. There is no disclosure in said patent of esterification of polyvinyl alcohol.